Hydrofoil watercraft



Oct. 26, 1965 R. BARKLEY HYDROFOIL WATERCRAFT 3 Sheets-Sheet 1 Filed Nov. 4, 1963 22F INVENTOR. fP/CHA/PD L BAR/(1.5V

A-f/orur W Oct. 26, 1965 R. 1.. BARKLEY HYDROFOIL WATERCRAFT 5 Sheets-Sheet 2 Filed Nov. 4, 1963 m mvE WQQQQWEEK I N VE N TOR. zQ/CH/WO A. EAR/(L67 A Horny Oct. 26, 1965 BARKLEY HYDROFOIL WATERCRAFT 3 Sheets-Sheet 5 Filed Nov. 4, 1963 INVENTOR. P/a/A/w BARKLEY United States Patent 3,213,818 HYDRGFOIL WATERCRAFT Richard L. Barkley, 2281 Byron, Palo Alto, Calif. Filed Nov. 4, 1963, Ser. No. 321,203 19 Claims. (Cl. 11466.5)

This invention relates to a watercraft of the hydrofoil type and more particularly to a novel, variable dihedral foil arrangement for control of the watercraft.

Hydrofoil supported watercraft are well known and generally include a hull means which is capable of being supported above the surface of the water on hydrofoils when the craft is propelled at a sufiiciently high speed. When the craft is stopped or moving at a very low speed, it is supported in the water as a displacement craft. At sufficient speeds and with a proper angle of incidence of the foil means, a vertical lift is provided by the said foil means to lift the hull out of the water for travel above the water surface. The attitude of the watercraft including its pitch and roll and the distance of the craft above the surface of the water may be controlled by controlling the hydrofoils. I

An object of this invention is the provision of a watercraft of the hydrofoil type having an improved hydrofoil configuration.

An object of this invention is the provision of a hydrofoil means for a watercraft for increased stability in roll and improved ability to control the roll of the craft.

An object of this invention is the provision of a hydrofoil-type watercraft having variable dihedral foils which may be controlled for control of the attitude of the watercraft.

An object of this invention is the provision of an improved hydrofoil arrangement for watercraft which may be simply and easily operated by means of linear actuating mechanism.

These and other objects and advantages of the invention are achieved by means of a hydrofoil system which includes at least one pair of movable foils extending generally athwartship beneath the hull of the watercraft. The foils are adapted for use in either a fully submerged or a surface piercing system wherein they remain submerged at all times during operation of the watercraft or pierce the surface during operation, respectively. Regardless of the system, the foils remain at least partially submerged at all times to provide lift during operation. They are pivotally mounted for swinging dihedrally, and means for pivoting the foil to change the dihedral angle thereof is provided. By simultaneous control of the dihedral angle of the foils in the same direction, the lift and thus the pitch of the watercraft is controlled; By independent control of the foils, or simultaneous differential operation thereof, in opposite directions, the rolls of the watercraft may be controlled. Also, with the dihedral foils, the natural roll stability of the watercraft is improved.

In the drawings wherein like reference characters refer to the same parts in the several views;

FIGURE 1 is a side elevational view of a watercraft supported on a fully submerged hydrofoil system constructed in accordance with the principles of this invention, the Watercraft being shown dynamically supported on the foils with the hull of the craft above the water surface;

FIGURE 2 is a fragmentary front elevational view of the hydrofoil arrangement shown on the craft of FIG- URE 1;

FIGURE 3 is a diagrammatic view of a gyroscopicstabilization system for use with the hydrofoil-supported craft shown in FIGURES 1 and 2;

FIGURE 4 is a fragmentary front elevational view of a modified form of hydrofoil arrangement embodying this invention;

ice

FIGURE 5 is similar to FIGURE 4 only showing another modified form of hydrofoil arrangement; and

FIGURE 6 is a cross-sectional view taken on line 66 of FIGURE 5.

Reference is now made to FIGURE 1 of the drawings wherein there is shown a watercraft designated generally by the reference numeral 10 and comprising a hull 11 with a cockpit 12 and a motor 13 mounted adjacent the stern thereof. A propeller 14 is driven by the motor 13 for propulsion of the watercraft. If desired, the craft may be propelled by a submerged screw connected to a motor, or other conventional manner of watercraft propulsion, the invention not being limited to any particular propulsion means. Also, it will here be understood that the invention is not limited to any particular hull configuration. For example, the hydrofoil system may be employed on a catamaran as well as other conventional hull arrangements.

Rigidly attached to the port and starboard sides of the hull 11 and extending downwardly therefrom are a pair of forward struts designated generally by the reference character 16, and a pair of aft struts designated generally by the reference character 17, only the starboard struts of each pair being visible in FIGURE 1. Novel forward and aft hydrofoil means 18 and 19 for the dynamic support of the hull of the watercraft above the surface of the water are located at the lower ends of the struts 16 and 17. The forward and aft hydrofoil means 18 and 19 may be of the same construction, if desired, and consequently only the forward hydrofoil means 18 togther with the supporting pair of struts 16 are described in detail hereinbelow, it being understood that the aft strut and hydrofoil means are of the same construction.

Reference is now also made to FIGURE 2 of the drawings wherein the forward pair of struts 16 are shown rigidly attached to the port and starboard sides of the hull and extending downwardly therefrom, the port and starboard forward struts being identified by the reference characters 16p and 16s, respectively. Extending athwartship between the struts 16p and 16s at the lower ends thereof beneath the hull 11 is a fixed hydrofoil 20 which may be afiixed at a predetermined desired angle with respect to the longitudinal or roll, axis of the watercraft, the longitudinal axis being identified by the reference numeral 23 in FIGURE 1 of the drawings. In accordance with this invention, the hydrofoil system includes a pair of dihedral foils designated 21p and 21s attached to the lower ends of the struts 16p and 16s opposite the ends of the fixed foil 20. The movable dihedral foils 21p and 21s are pivotally mounted on pins 22p and 22s attached to the struts 16p and 16s, which pins extend generally parallel with the roll axis, or longitudinal center line 23 of the craft. The dihedral foils 21p and 21s are movable between a lowered position, not shown, wherein the foils are substantially parallel and coplanar with the main foil 20, and a raised position shown in broken lines in FIGURE 2. The solid line position of the movable hydrofoil members in FIGURE 2 illustrates a mean position where the foils are normally positioned during operation. With increased dihedral angle, such as illustrated by the broken line position, the roll stability of the watercraft is increased. An advantage of the dihedral foil arrangement of this invention over conventional aileron-type control hydrofoils is the increased roll stability provided by the dihedral foils. Dihedral angle as applied in the specification and claims refers to the angle between the movable hydrofoil and the plane containing the longitudinal (or roll) and lateral (or pitch) axes of the watercraft.

By independent control of the dihedral angle of the foils 21p and 21s, or simultaneous control thereof in the opposite directions, eg., increasing the dihedral angle of one foil while decreasing the dihedral angle of the other foil, roll control of the watercraft is provided. In the control system diagram shown in FIGURE 3 and described hereinbelow roll control is effected by such simultaneous differential operation of the forward dihedral foils.

The vertical lift provided by the dihedral foils 21p and 21s may be controlled by the simultaneous control of the dihedral angle of the foils in the same direction. For example, with the foils in the illustrated solid line position shown in FIGURE 2, the foils provide more verti cal lift than when they are in the broken line, minimum vertical lift, position. Maximum vertical lift is obtained when the dihedral angle of the foils is reduced to zero, that is, when the movable foils extends horizontally outwardly in the plane of the main hydrofoil 20. With simultaneous control of the foils in the same direction the depth at which the foils operate under the surface of the water and the pitch angle of the watercraft may be controlled. It will here be understood that the foils employed in the novel hydrofoil system of this invention may be of any desired well-known cross-sectional shape; For example, they may be generally wedge-shaped, of the super-cavitating type, or they may be air-foil shaped, of the sub-cavitating type. It will be apparent that the invention is not limited to any particular foil cross-sectional shape.

In the control system diagram of FIGURE 3, the forward foils may be simultaneously controlled in the same direction in response to vertical heaving motion of the watercraft for depth control of the hydrofoil means, and the aft foils may be simultaneously controlled in the same direction in response to the pitch attitude of the watercraft for pitch control thereof. The stabilization control system of FIGURE 3 will be described in detail after the detailed description of the mechanical actuating mechanism for the hydrofoils which follows.

As best seen in FIGURE 2, means for pivotally actuating the dihedral foils 21p and 21s include fluid cylinders 25, which cylinders include pistons 26 having piston rods 27 attached thereto. Attached to the lower free ends of the piston rods 27 are guide blocks 28 which are adapted to slide in suitable ways, not shown in FIGURE 2, within the struts 16p and 16s. A link 29 extends between each of the guide blocks 28 and the associated dihedral foils, and is pivotally connected at opposite ends by pins 30 and 31. Slots 32 are pivoted in the sides of the struts through which the links 30 extend, one such slot being shown in FIGURE 1. It will be understood that in the illustrated fully submerged hydrofoil system the foils, as well as the actuating mechanism, remain submerged at all times under normal operating conditions whereby ventilation is reduced to a minimum. Only the struts 16p and 16s cut the water surface during operation as a hydrofoil watercraft. As mentioned above, however, the hydrofoil system may be applied to a surface piercing system wherein the dihedral foils pierce the water surface during normal operation.

The piston cylinder actuators 25 are connected to a suitable source of fluid pressure, not shown. Control of the fluid pressure to the cylinders may be exercised by manual or automatic control means. In FIGURE 3, an automatic gyroscopic stabilized system is shown for control of the actuating cylinders 25. Although a particular control system is shown and described hereinbelow, it will be apparent that the novel controllable hydrofoil arrangement of this invention is not limited to use with such a control system. i A Reference is now made to FIGURE 3 of the drawings wherein there is diagrammatically shown a suitable gyroscopic stabilization control system for control of the forward and aft hydrofoil means 18 and 19 for roll, pitch and vertical heave control of the watercraft 10 shown in FIGURE 1. A gyroscope 41 provides roll and trol thereof while a vertical accelerometer 42 provides vertical acceleration information on the watercraft for vertical heave control thereof.

The gyroscope 41 includes a rotor 43 adapted for rotation about a vertical axis within the usual gimbal rings, which rings are suspended for rotation about longitudinally and transversely extending axes of the watercraft. Pickups 44 and 46 for sensing the roll and pitch attitude of the watercraft and providing electrical signals proportional thereto are included in the gyroscope construction. A pair of equal potential outputs is obtained from the roll pickup 44 and fed to port and starboard servo amplifiers 47 and 48 through lead wires 49 and 51, respectively. The servo amplifiers 47 and 48 are also supplied with electrical feedback signals from feedback transducers 52 and 53 suitably connected to the port and starboard hydrofoils 21p and 21s, respectively, through mechanical linkage designated 54 and 55. Voltage outputs are obtained from the feedback transducers 52 and 53 which outputs are fed through leads 56 to the port and starboard servo amplifiers. The transducer outputs are dependent upon the position of the hydrofoils 21p and 21s, respectively, and when the feedback signals are not equal to the input signals supplied to the servo amplifiers 47 and 48, error signals are produced at the outputs from the servo amplifiers, which signals are connected through lead wires 57 and 58 to servo control motors included in servo valves 59 and 61. A suitable source of hydraulic fluid pressure, not shown, is adapted for connection through the servo valves and through fluid lines 62 to the piston actuators 25. Upon receipt of error signals from the servo amplifiers 47 and 48 the servo valves 59 and 61 are actuated in a manner to cause the pistons of the associated operators 25 to move in opposite directions. The dihedral angle of the one forward hydrofoil is thereby increased while that of the other hydrofoil is decreased, the movement of the forward hydrofoils being such as to counteract the roll of the watercraft.

In the illustrated control system of FIGURE 3, the forward hydrofoil means 18 are also made to respond to the vertical motion of watercraft and, in this manner, to effect a control on the depth at which the hydrofoils operate under the water surface. To this end there is provided a vertical accelerometer 42 having an electrical output related to the vertical acceleration of the watercraft. The output from the accelerometer is fed to an integrator 66 whereby the integrator output is related to the vertical velocity of the watercraft. The output from the integr-ator is then fed to the port and starboard servo amplifiers 47 and 48 through leads 67 and 68 to cause the forward actuators 25 to move simultaneously in the same direction. The forward hydrofoils 21p and 21s are thereby moved in the same direction to simultaneously increase or decrease the dihedral angle thereof to control the lift provided thereby. The connections are such that if the watercraft accelerates upwardly, the dihedral of the forward foils increases to reduce the lift thereof, thereby causing the watercraft to descend in the water. With a downward acceleration of the watercraft, an opposite signal is supplied to the servo amplifiers for movement of the forward hydrofoils in the opposite direction.

As mentioned above, the gyroscope 41 provides an electrical output from the pickup unit 46 which is related to the pitch of the watercraft. This pitch control output, or signal, is fed to a pitch servo amplifier 71 through a lead wire 72. The pitch servo amplifier is also supplied with an electrical feedback signal from a feedback trans ducer 73 electrically connected thereto through a lead wire 74. The feedback transducer is mechanically connected through linkage 76 to the aft hydrofoils 21p and 21s, and provides an output voltage which is dependent upon the position of the said aft dihedral foils. When the feedback signal does not cancel the input signal to the pitch servo amplifier 71, an error signal is produced at the output from the said amplifier, which signal is fed through lead wire 77 to the control motor included in the fluid pressure through means, not shown. from the servo valve 78 is connected through fluid lines for simultaneous actuation thereof.

servo valve 78. As with the other servo valvesdescribed above, the servo valve 78 is connected to a supply of The output 79 and 81 to the port and starboard aft piston actuators .2 5for the control of the respective port and starboard aft foils 21p and 21s. The single pitch amplifier 77 thereby controlsboth the aft dihedral foils for simultaneous movement thereof in the same direction for control of the liftprovided thereby. The direction of actuation of the aft dihedral foil is such as to produce a counter torque about the pitchaxis of the craft for stabilizing the craft in pitch attitude.

F As mentioned above, the control system of FIGURE 3 is merely illustrative of a type of system which may be employed for stabilizing the watercraft of this invention.

In some installations it may be desirable to provide for which the main hydrofoil shown in FIGURE 2 has been eliminated. As seen in FIGURE 4, the dihedral foils 21p and 21s are each pivotally mounted on pins 22p and 22s at the lowerend of a single strut 16', which strut extends downwardly from the hull 11. A single actuating cylinder 25 is provided at the upper end of the strut and is provided with a piston 26 connected to a guide block 28 through a piston rod 27. In the illustrated arrangement the links 30 for both dihedral foils 21p and 21s are pivotally connected by pins 29 to the one block 28. Thus it will be seen that both dihedral foils 21p and 21s are under control of a single piston operator With the dihedral foils in the illustrated solid line position, the craft operates under maximum roll stability. In the broken line position of the dihedral foils the craft operates with maximumilift. Thus, while control of the stability and lift is provided, there is no control of the roll attitude of the craftwith this arrangement if the dihedral foils are supported on a strut 16 which extends downwardly from the center of the hull. If, on the other hand, the arrangement illustrated in FIGURE 4 comprises one of a pair of such arrangements in side-by-side (i.e., laterally spaced) relation, it will be apparent that roll attitude control of the watercraft could be effected by the simultaneous actuation of the foil means pivotally secured to one strut since said foil means would then be spaced from the longitudinal center of watercraft.

" It will be readily apparent that this arrangement would be well suited for use as the aft foil means 19 on the watercraft shown in FIGURES 1 and 2 when used with the control system of FIGURE 3 wherein no independent control of the aft movable foils is provided. The control system of such a hydrofoil arrangement would also be simplified since only a single piston actuator is employed' for actuation of both dihedral foils.

For the same degree of control as provided by the hydrofoil arrangement of FIGURES 1 and 2, i.e.,for individual control of the movable hydrofoils, the arrangement of FIGURES 5 and 6 may be employed. Referring now to FIGURES 5 and 6, the illustrated arrangement is similar to that shown in FIGURE 4 except the dihedral foils 21p and 21s are individually controllable in their dihedral angles. As with the arrangement of FIGURE 4, the dihedral foils 21p and 21s are supported at the lower end of a single strut designated 16". The strut 16" is of somewhat larger size than the strut 16' in order to accommodate a pair of actuating cylinders 25 connected by piston rods 27 to individual guide blocks designated 81p and 81.9. As seen in FIGURE 6 of the drawings, the guide blocks 81p and 81s operate within individ 6 ualways, 82p and 82s, respectively, the guide blocks being connected to the pivotal foilsthrough thelinkage29 and pins 30 and31. As withthearrangement of FIG- URES l and 2, thedihedral foils 21p and 21s areindividually controllable for roll control of the craft. It will be apparent that such an arrangement maybe used as the forward hydrofoil means 18 on the watercraft shown in FIGURES 1 and 2 with the stabilization control system shown in FIGURE 3.

The invention having been described in detail in accordance with the requirements of the patent statutes, various other changes and modificationswill suggest themselves to those skilled in this art. For example, although piston actuators are illustrated for control of the dihedral foils, it will be readily apparent that other actuating means may be employed, if desired, such as mechanical actuators. For example, a rack and. pinion arrangement could be used, if desired, as well as other linear actuating devices. It is intended that this and other such changes and modifications shall fall within the spirit and scope of the invention as recited in the following claims.

What is claimed is:

1. In a watercraft the combination of a hull, support means depending from the hull, said support means being fixedly positioned relative to said hull and piercing the water surface during operation of the watercraft, foil means pivotally mounted on the support means to swing dihedrally about pivot axes adjacent the submerged free end of said support means, said pivot axes being in fixed position relative to said fixedly positioned support means and extending generally parallel to the roll axis of the watercraft, said foil means being adapted to remain at least partially submerged during operation ofthe watercraft, and means connected to the foil means to pivot the same for control of the dihedral angle thereof between high and low vertical lift positionsfor attitude control of the watercraft when in motion.

2. The watercraft as defined by claim 1 wherein said watercraft is adapted for rudderless attitude control by control of the dihedral angle of said foil means.

3. A hydrofoil supported watercraft having water foil means and ahull means adapted for support outof the .water by the water foil means and support means depending from the hull and supporting said water foil means, said support means being stationary relative to the hull and piercing the water surface during operation of the watercraft, said foil means including at least one pair of movable foils extending generally athwartship beneath the hull means, means pivotally mounting the movable foils on the support means on pivot axes adjacent the submerged free end of said support means, said pivot axes being fixed relative to said stationary support means and extending generally parallel to the roll axis of the watercraft, the said movable foils being adapted to remain at least partially submerged at all times during operation of the watercraft, and means for pivoting the foils about said pivot axes to change the dihedral angle thereof between .high and low vertical lift positions for attitude control of the watercraft when in motion.

4. The watercraft as defined by claim 3 including control means coupled to said means for pivoting the foils for rudderless attitude control of the watercraft by control of the dihedral angle of said foils.

5. The watercraft recited in claim 3 including control means coupled to said means for pivoting the foils for roll stabilization and lift control of the watercraft, the lift being greatest with the movable foils set-at the smallest dihedral angle and least when they are at the largest dihedral angle. i

6. The watercraft recited in claim 3 including control means coupled to said means for pivoting the foils for individually pivotally controlling the movable foils for roll control of the watercraft.

7. A hydrofoil supported watercraft having water foil means and a hull means adapted for support out of the water by the water foil means and at least one strut extending downwardly from the hull and supporting said water foil means, said strut being stationary with respect to said hull with the lower end thereof submerged during operation of the watercraft, said foil means including at least one pair of movable foils extending generally athwartship beneath the hull means and adapted to remain at least partially submerged at all times during operation of the watercraft, means pivotally mounting the said movable foils at the lower end of said strut for pivotal movement about pivot axes fixed relative to said strut and extending generally parallel to the longitudinal axis of the watercraft, and means for pivoting the foils to change the dihedral angle thereof between high and low vertical lift positions for attitude control of the watercraft when in motion.

8. The watercraft as defined by claim 7 including control means coupled to said means for pivoting the foils for rudderless attitude control of the watercraft by control of the dihedral angle of said foils.

9. A hydrofoil supported watercraft having a hull means adapted for support out of the water by water foil means, said watercraft including at least one pair of struts extending downwardly from the hull, said struts being stationary with respect to the hull, with the lower ends thereof submerged during operation of the watercraft, a main fixed foil extending athwartship between the said struts, a pair of movable foils pivotally mounted adjacent the submerged lower end of said struts and extending outwardly from the ends of said main foil, said movable foils being pivotable about pivot axes fixedly positioned relative to said struts, and means for pivoting the movable foils to change the dihedral angle thereof between high and low vertical lift positions for attitude control of the watercraft when in motion.

10. The watercraft as defined by claim 9 including control means coupled to said means for pivoting the movable foils for rudderless attitude control of the watercraft by control of the dihedral angle of said movable foils.

11. A hydrofoil supported watercraft having water foil means and a hull means adapted for dynamic support out of the water by the water foil means and support means depending from the hull and supporting said water foil means, said support means being in fixed relative position with the hull and extending downwardly into the water during operation of the watercraft, said foil means including at least two pairs of movable foils, means pivotally mounting said foils on the said support means on axes at the underwater end of said support means, which axes are in fixed relative position with said support means and extend generally parallel to the roll axis of the watercraft, the said foils extending generally athwartship beneath the hull means with one pair below the forward end of the hull means and the other pair below the aft end thereof, the said movable foils being adapted to remain at least partially submerged at all times during operation of the watercraft, and means for pivoting the foils to change the dihedral angles thereof between high and low vertical lift positions for attitude control of the watercraft when in motion.

12. The watercraft recited in claim 11 wherein the support means includes at least one strut extending downwardly amidships from the hull, one pair of said foils being pivotally mounted on the strut adjacent the lower end thereof.

13. The watercraft recited in claim 11 wherein the support means includes at least one pair of struts extending downwardly from the hull at the port and starboard sides thereof, a main fixed foil extending athwartship between the struts adjacent the lower free ends thereof, one pair 'of foils being pivotally mounted on said pair of struts with one foil pivotally mounted on one strut and the other foil pivotally mounted on the other strut, the said one pair of movable foils extending outwardly from the 8 ends of the said main foil and being pivotal from positions substantially coplanar with the main foil. I

14. The hydrofoil supported watercraft recited in claim 11 including a control system for controlling said means for pivoting the foils, said control system including means for controlling the one pair of foils for simultaneous movement in the same direction in response to vertical heaving motion of the watercraft to counteract said heaving motion, means controlling the said one pair of foils for differential movement in opposite directions in response to roll motion of the watercraft to counteract said roll motion, and means for controlling the other pair of foils for simultaneous movement in the same direction in response to pitch motion of the watercraft to counteract said pitch motion.

15. The watercraft as defined by claim 11 including control means coupled to said means for pivoting the movable foils for rudderless attitude control of the watercraft by control of the dihedral angle of said movable foils.

16. A hydrofoil supported watercraft having water foil means and a hull means adapted for support out of the water by the water foil means and at least one strut extending downwardly from the hull and supporting said water foil means, said foil means including at least one pair of movable foils extending generally athwartship beneath the hull means and adapted to remain at least partially submerged at all times during operation of the watercraft, means pivotally mounting the said movable foils at the lower end of said strut for pivotal movement about pivot axes extending generally parallel to the longitudinal axis of the watercraft, and means for pivoting the foils to change the dihedral angle thereof between high and low vertical lift positions for attitude control of the watercraft when in motion, said means for pivoting the foils including piston and cylinder means within the strut, and links pivotally connecting the piston means to the foils for pivotal actuation of said foils.

17. A hydrofoil supported watercraft having water foil means and a hull means adapted for support out of the Water by the water foil means and at least one strut extending downwardly from the hull and supporting said water foil means, said foil means including at least one pair of movable foils extending generally athwartship beneath the hull means and adapted to remain at least partially submerged at all times during operation of the watercraft, means pivotally mounting the said movable foils at the lower end of said strut for pivotal movement about pivot axes extending generally parallel to the longitudinal axis of the watercraft, and means for pivoting the foils to change the dihedral angle thereof between high and low vertical lift positions for attitude control of the watercraft when in motion, said means for pivoting the foils including piston and cylinder means within said strut, and links extending through slots in the strut and pivotally connecting the piston means to the foils for pivotal movement thereof.

18. A hydrofoil supported watercraft having water foil 'means and a hull means adapted for support out of the water by the water foil means and at least one strut extending downwardly from the hull and supporting said water foil means, said foil means including at least one pair of movable foils extending generally athwartship beneath the hull means and adapted to remain at least 19. A hydrofoil supported watercraft having a hull means adapted for support out of the water by water foil means, said watercraft including at least one pair of struts extending downwardly from the hull, a main fixed foil extending athwartship between the said struts, a pair of movable foils pivotally mounted adjacent the lower end of said struts and extending outwardly from the ends of said main foil, and means for pivoting the movable foils to change the dihedral angle thereof between high and low vertical lift positions for attitude control of the watercraft when in motion, said means for pivoting the movable foils including piston actuators located within each of the struts, and links pivotally connecting said piston actuators to the said movable foils for pivotal actuation of said foils.

References Cited by the Examiner UNITED STATES PATENTS Noll 114-665 Bussei 11466.5

Von Schertel 11466.5

Bader 114-66.5

Bader et al. 11466.5

Wilterdink 114-665 Von Schertel 11466.6

MILTON BUCHLER, Primary Examiner.

15 FERGUS S. MIDDLETON, Examiner. 

1. IN A WATERCRAFT THE COMBINATION OF A HULL, SUPPORT MEANS DEPENDING FROM THE HULL, SAID SUPPORT MEANS BEING FIXEDLY POSITIONED RELATIVE TO SAID HULL AND PIERCING THE WATER SURFACE DURING OPERATION OF THE WATERCRAFT, FOIL MEANS PIVOTALLY MOUNTED ON THE SUPPORT MEANS TO SWING DIHEDRALLY ABOUT PIVOT AXES ADJACENT THE SUBMERGED FREE END OF SAID SUPPORT MEANS, SAID PIVOT AXES BEING IN FIXED POSITION RELATIVE TO SAID FIXEDLY POSITIONED SUPPORT MEANS AND EXTENDING GENERALLY PARALLEL TO THE ROLL AXIS OF THE WATERCRAFT, SAID FOIL MEANS BEING ADAPTED TO REMAIN AT LEAST PARTIALLY SUBMERGED DURING OPERATION OF THE WATERCRAFT, AND MEANS CONNECTED TO THE FOIL MEANS TO PIVOT THE SAME FOR CONTROL OF THE DIHEDRAL ANGLE THEREOF BETWEEN HIGH AND LOW VERTICAL LIFT POSITION FOR ATTITUDE CONTROL OF THE WATERCRAFT WHEN IN MOTION. 